Smart Pigging

Descriptive Image

Merlin Inspection Technology

Our Merlin Inspection Technology has progressed through research and development, steadily improving in stages of capability, performance and reliability.

Once the decoking operation has been completed, our Merlin Smartpig is driven by water through the internal passageway of a pass or coil. It uses ultrasound technology to internally scan fired heater tubes, whilst simultaneously recording radius and wall thickness measurements to identify flaws and defects.

The current development stage is proven to allow passage through plug headers without modification. Using a single body of specially prepared composite material, the Merlin Mark IV technology is designed to have narrow passageway capability and has been used in tube circuits which include plug headers (also referred to as box headers or mule ears), featuring a central crossover passage with a 3-inch diameter.

Navigating through 180° u-bends is made possible with the Mark IV Intelligent Pig, which can pass through 3 inches schedule 160 tubes with an internal diameter of 2.5 inches (63.5mm).


Key Features

Key Features Pig
Line A

8hrsBattery Life

Line B

0.3 - 0.8m/s (0.9 - 2.6ft/s)Running Speed

Line B

30,720p/m (9,366p/ft)Individual Wall Thickness

Line C

Bidirectional Bidirectional

Line F

63.5 - 304.8mm (2.5 - 12 inches)Tube Diameter Range (Internal)

Line G

+/-0.1mm (0.0039 inches)Static Accuracy (Wall Thickness)

Line G

±0.75%ID Accuracy (Full Scale)

Line F

+/-50mm (1.97 inches)Axial Location Accuracy

Smart Pigging - What Can It Inspect?

What Can It Inspect?

  • Process piping within all types of fired heaters (including convection, radiant and steam coils)
  • Convection coils containing finned or studded tubing
  • HRSG/OTSG boilers
  • Fired heater configurations containing 1D, short-radius return bends, plug headers, mule-ears, flat-back bends
  • Fired heaters containing multiple tube diameters throughout the process coil
  • Arbour coils
  • Fired heaters containing common headers
  • “Unpiggable” pipelines up to 12-inch diameter
  • Transfer lines
  • Slop/wastewater lines


Ability to detect and categorise the following flaws and defects:

  • Internal metal loss (corrosion, abrasion, erosion etc.)
  • External metal loss (corrosion, abrasion, erosion etc.)
  • Areas of pitting
  • Bulging
  • Swelling
  • Ovality
  • Manufacturing defects
  • Internal fouling

Advantages of
Smart Pigging

Manual UT

Exterior surface – requires preparation work

Limited access – difficulty in reaching wall-side surface

Scaffolding required

Unable to inspect convection coils

Time consuming

Less coverage (2-3% of coil’s surface)

Unable to detect pitting

Unable to detect creep damage

Lots of guess work involved in FFS

Cannot produce C-scans

True corrosion patterns are difficult to model


Smart pigging

No physical access to the coil required

Decoking required – SP then used to determine
success of decoking

Ability to inspect convection coils including finned
and/or studded tubes

Minimal downtime (A typical smartpig run
lasting 30 mins)

Detection and quantification of localised
defects/creep damage

Typically 30,720 measurements per metre length of tubing

Full colour coded 3D models of process coils/tubes

Full contour profiles for accurate Level 2 FFS Assessment inputs

3D Interactive View

Cokebusters proprietary 3D analysis software, Insight Vision, offers clients a fully interactive, immersive view of individual fired heater process piping. The colour mapped 3D models provides the data analyst with a comprehensive display of dimensional details, including wall thickness, internal radius, outside radius and coke thickness, resulting in a rapid evaluation of flaws and anomalies utilising its vast array of sophisticated assessment tools. Here is a basic version of Insight Vision displaying a radiant coil with severe wall loss caused by flame impingement.

Smart Pigging - Baseline

Baseline Inspections

There are huge benefits to carrying out a baseline inspection prior to coils being entered into commercial service. In addition to identifying any issues before coils are put into service, an initial smartpig inspection will remove the uncertainty caused by mill tolerances during the manufacturing process, and equip engineers with the data required to confidently make decisions on maintenance, repair and inspection activities.

Baseline inspections should ALWAYS be carried out during commissioning to maximise the accuracy of all future Fitness for Service and Remaining Life Assessments.

Although we proudly offer a full combined service here at Cokebusters, our inspection team has proven ability to work alongside alternative decoking companies throughout the world. Feel free to get in touch with us today to discuss whatever needs and requirements you may have, and we’ll be happy to help.


Inspection Reports

Data analysis is carried out by our fully qualified inspection technicians throughout the on-site inspection process. Any flaws or anomalies are immediately flagged and raised to the client as soon as they are identified.

We present the inspection field report to the client within 24 hours of the final inspection run carried out on the heater. The field report contains details, data tables and graphs from which the client can make informed decisions on any repair work required.

We issue the final inspection report to the client within 7 days of leaving site. The final report contains extensive detail on any flaws/anomalies found as well as full data, maps, C-scans, data tables and graphics. A downloadable copy of our 3D viewing software is also supplied to the client upon submission of the report.

Example Reports

A full Merlin specification and sample inspection report is available upon request.

Contact our Merlin Inspection
Team today with your enquiry